This invention relates to hydraulic energy systems, and particularly to systems which utilize the potential energy of submerged air bubbles produced by a waterfall.
In the past, a number of proposals have been made for hydraulic air compressors in which the kinetic energy of a stream of water falling from a higher level to a lower lever is utilized to compress air. Among such proposals is the one described in U.S. Pat. No. 1,449,523, dated May 27, 1923, wherein a conduit constructed underneath a dam is provided with an air collection chamber buried below the dam. The upstream end of the conduit is in the form of a widened vertical conductor, extending upwardly into the body of water behind the dam, and having an air duct disposed in it in such a way as to provide a surrounding annular passage for the flow of water. The upper end of the air duct communicates with the atmosphere, and a plurality of short air suction nozzles project radially from the duct into the annular passage. An overhanging device is provided above each nozzle to increase the flow of air from the air duct into the stream of water flowing through the annular passage. Bubbles formed as a result of the action of the nozzles are carried by the stream through the conduit, and air from the bubbles is collected under pressure in the submerged chamber.
Similar systems utilizing vertically extending conduits and special air introduction devices are described in McGinn British Pat. No. 210,228, dated Jan. 31, 1924, Taylor U.S. Pat. No. 543,410, dated July 23, 1895, and in Kirshner, Fluid Amplifiers, McGraw-Hill, 1966, pp. xii-xiii, the latter showing a pneumatic system for lifting water installed by Priestly in 1890 at Snake River Desert, Idaho.
In the McGinn and Taylor systems, suction devices are used to introduce air into the downwardly flowing stream of water. In the Priestly apparatus a stream of water was trained into a pipeline extending down a bluff in such a way that a considerable quantity of air was carried down along with the water in the pipeline for collection in an inverted air reservoir near the bottom of the bluff.
The present invention represents an improvement over the foregoing systems in that it requires no vertically extending water conduit, and no special apparatus for entraining air into the stream of water flowing through the conduit. In accordance with the invention, advantage is taken of the fact that a stream of water falling into a body of water produces agitation at the surface which results in the formation of bubbles, and carries the bubbles thus formed a distance below the surface. More specifically, the impact of the falling stream of water onto the surface of the body of water is believed to result in the repeated formation of depressions or pockets in the surface of the water. These pockets are closed by reason of the continuous inward flow of water at the surface, and air is entrapped in the form of bubbles. The downward momentum of the falling stream then carries the bubbles for a distance underneath the surface where they are compressed by the head of water in accordance with their depth.
In many cases, these bubbles rise from a considerable depth, and therefore carry substantial potential energy in the form of air pressure. This potential energy is present in natural and artificial waterfalls. In many hydroelectric plants, there is an overflow at some time during the daily operation of the plant which results in an artificial waterfall.
In each case, bubbles are carried underneath the level of a body of water to a depth such that substantial amounts of potential energy are produced.
The potential energy of the submerged bubbles is captured by means of an open-bottomed collection tank which is at least partially submerged and located in a position so as to collect the maximum amount of entrained air. A pressure greater than atmospheric is built up in the collection tank which may be utilized in various ways.
The collected air may be simply stored under pressure for later use, or it may be used directly at the pressure at which it is collected.
Alternatively, the collection tank may be interconnected with a pressure transformer in order to produce air under high pressure. In conjunction with the pressure transformer, valving may be so operated as to produce a reciprocating action so as to produce a sustained flow of air under high pressure.
The high pressure air flow so produced may be used to operate and air-lift pump to raise water, either from the body of water into which the waterfall flows or from another body of water, to a high level.
Finally, the pressure so produced may be used to operate a series of specially adapted air-lift pumps in accordance with the invention which may be utilized to lift water to any desired height.
This high pressure air may also be used wherever compressed air is useful; for example, in the operation of air tools, or in supercharging stationary internal combustion engines.
In accordance with an alternative embodiment of the invention, a reciprocating piston motor or turbine is positioned in a path of flow between a part of a body of water containing relatively few air bubbles and another part of the body of water into which a relatively large quantity of bubbles has been carried by a stream of falling water. Flow through this path takes place by virtue of the difference in densities in the two parts, and is available to do useful work.
The principal object of this invention is to produce useful work from falling water, while eliminating the need for special and elaborate flow passages and air entrainment devices formerly considered necessary.
Another object of the invention is to provide a simple and effective apparatus for producing useful work from a stream of falling water.
Further objects will be apparent from the following detailed description when read in conjunction with the drawings.